The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
A stent is a tubular device that is placed into a body lumen, such as a blood vessel, of a patient to for example provide support to a weakened area or to maintain patency of a lumen within the body. Ureteral stents are a specific type of stents that are optimized for use in a patient's ureter. A ureteral, or ureteric, stent may be used to support a weakened ureter due to a variety of complications or to reopen a ureter that has been obstructed by a kidney stone.
The majority of ureteral stents used today are flexible polymer tubes that include drainage side ports and loops at each end (FIG. 1). A guide wire is inserted into the patient's ureter and the stent is delivered over the guide wire and positioned within the patient's ureter. Polymer ureteral stents are designed to be flexible to reduce patient discomfort. However, polymer ureteral stents have several drawbacks. First, polymers degrade at a greater rate than other biocompatible materials and therefore they are only approved to be used for a short period of time (e.g. 6 months) before they must be removed from the patient and replaced. Second, polymers have a high surface friction, thus necessitating the use of a hydrophilic coating to prevent unwanted friction between the stent and the ureteral wall to prevent or limit damage to the ureteral wall. Third, polymer stents have low radial strength, meaning they are unsuitable for use in patients where a high radial strength is necessary to properly support the ureteral wall. Fourth, because the polymer stents are designed to be flexible, tensile strength and torque-ability is sacrificed, which may result in insufficient support of the ureteral wall.
Thus, it is desirable to provide a ureteral stent with high tensile, torque, compressive, and radial strength while maintaining maximum flexibility for patient comfort. Additionally, it is desirable to provide a ureteral stent that allows for passage over a guide wire and may remain indwelled in a patient for a long period of time.